184 REPORT OF STATE BOARD OF HORTICULTURE. 



of the influence of climate, soils, and fertilizers, as well as of those pertain- 

 ing to fruit curing, will require much more exhaustive work than this sta- 

 tion has yet been able to do. These are questions requiring a large amount 

 of time and painstaking labor, and, amid the multitudinous duties pressing 

 in other directions, progress will necessarily be slow. 



COMPOSITION OF THE PRUNE. 



The composition of the prune may be expressed as follows : 



1 Water. , c, 



I (1) Juice. ! |"4-- 



^ . I ^ Soluble Solids. I ^^S^^,,,ids. 



^™^^i .cellulose. ^ ^cids. 



1 (2) Pulp. - Carbohydrates. 

 ' Pectose. 



During the process of ripening the first division is increased much at the 

 expense of the second. 



Water — This constitutes a very large proportion of all fruits in the fresh 

 state, ranging from about sixty-five per cent, to ninety per cent. In the 

 prune it ranges from sixty-five to eighty-five per cent, as will be seen on re- 

 ferring to the tables which appear elsewhere in this bulletin. This water 

 is no different from that occurring elsewhere in nature. 



Suy(ir — This exists in fruits mainly as grape or fruit sugar which is widely 

 ditt'used in nature. It is much less sweet than cane sugar. In fruits this 

 sugar is developed from starch and cellulose during the process of ripening 

 as will be discussed later. 



Pectous bodies — These important bodies are scarcely ever wanting in fruit 

 juices. They are substances, which, on proper boiling of the juice, causes 

 it to form a jelly. The gummy exudation on a baked apple consists of a 

 mixture of these pectous bodies. The pectin of the juice is formed by a 

 chemical change from the pectose of the pulp which is a very characteristic 

 constituent unripe fruit. 



Albumenous substances — This is a class of bodies which contains about six- 

 teen per cent, of nitrogen and is commonly estimated by a determination of 

 that element. They comprise vegetable albumen, fibrin, and gluten. They 

 constitute a very important class of bodies inasmuch as it is their function, 

 and theirs alone, to form flesh or muscle in the body. 



The adds — The acids of fruit juices are malic and citric, the former con- 

 stituting the chief sour principle in the case of prunes. These acids are 

 usually accompanied by a small amount of tartaric acid. 



Cellulose or vegetable fibre — This occurs in all parts of all plants. It is this 

 which gives strength and toughness to vegetable matter and forms its frame- 

 work. It is closely related to starch from which it is formed. It is well 

 rejiresented by the fibre of cotton, hemp, and flax. 



Asli — The ash, or inorganic constituent of fruit, represents the mineral 

 matter which has been removed from the soil. It comprises various salts of 

 potassium, sodium, magnesium, iron, calcium, etc., combined with phos- 

 phoric, sulphuric, hydrochloric, and silici acids. 



